His father was a whaling ship captain, and Frederick spent much of his youth mastering boat handling.

[3] Frederick Slocum took a leave of absence 1908–9 to study at the Royal Astronomical Observatory in Potsdam, Germany.

In 1914, Slocum became the first professor of astronomy at Wesleyan University, where he planned and supervised the construction of Van Vleck Observatory.

During World War I, he was absent while training merchant captains in the skill of navigation for the United States Shipping Board.

He also spent some time at Brown University as professor in charge of the Department of Naval Science, before returning.